Sensors & Software is proud to introduce the latest evolution of pulseEKKO® – the Ultra Receiver.

The new pulseEKKO® Ultra Receiver builds on the world-renowned capability of the pulseEKKO® GPR brand. Data acquisition is now thousands of times faster than before. This has huge implications for collecting GPR data:

Stack GPR traces up to 65,536 times, with little to no reduction in collection speed.

Reduce the noise floor to see GPR signals up to 100 times smaller than before.

All this means incredible opportunities for research and advancements in existing GPR applications.

Random background noise limits GPR systems from detecting the weak signals from deep in the subsurface. Using the increased speed to stack the GPR traces more times results in deeper GPR penetration than ever before. Stacking decreases the random noise floor and increases the imaging depth. The Ultra Receiver stacks thousands of times, allowing GPR practitioners to see GPR signals 100 times smaller than before. High stacking increases the dynamic range of the data from 16-bit to 32-bit.

The example data below shows how the depth of penetration is about 25 meters when the GPR data is stacked 32 times (left). The depth of penetration more than doubles to over 50 meters when the data is stacked 32,000 times (right).

Figure 1:

The depth of GPR signal penetration increases from about 25 meters to over 50 meters when the number of stacks is increased from 32 (left) to 32,000 (right). The GPR lines were collected at that same site; an old limestone quarry in Rockwood, Canada.

The increased sensitivity of the Ultra receiver overcomes the regulatory emission limits in the USA, Canada and Europe, that currently constrain transmitter power and limit GPR exploration depth. With the highest data quality available in a GPR system, pulseEKKOs are uniquely suited to take full advantage of the Ultra Receiver’s capabilities.

Upgrade bundles are available to use the Ultra Receiver with pulseEKKO® 100 or pulseEKKO® PRO low frequency antennas.

How the Ultra Receiver Works

The “Depth of Penetration” for GPR is the depth (or two-way travel time) at which the GPR signal amplitudes, shown in blue below, attenuate to the same level as the background noise, shown in yellow.

Figure 2:

GPR signals are present but masked by stronger, random, background radio noise, called the Noise Floor. Lowering the Noise Floor by stacking GPR data traces allows the weaker GPR signals to be seen.

Since there are GPR signals buried below the noise floor, this means that the depth of penetration increases if the noise floor decreases.

Notice the GPR line is now a new section showing much greater depth of penetration (60+ metres) than before.

GPR signals are recorded between the peak amplitude and the background noise level. The Ultra Receiver allows you to see deeper by reducing the background noise by two or more orders of magnitude – and see GPR signal more than 100 times smaller than before.

The Ultra Receiver does this by stacking. The idea of stacking is, rather than collect the GPR trace once and save it, we collect the GPR trace multiple times, average those multiple traces and only save the average trace.

Figure 3:

“Stacking” GPR traces by collecting the same trace multiple times, averaging and saving the average trace, increases the Signal-to-Noise ratio (SNR) by reducing the random noise.

This increases the “Signal to Noise Ratio”. This is done, not by increasing the GPR signal amplitude, but by decreasing the noise amplitude. The smaller the noise, the more GPR signal can be seen at greater depths.

The idea of decreasing the random noise is depicted above by the red part of the GPR trace. Notice how, the amplitude of the red noise in the saved trace gets smaller the more times we stack the trace.

Quantitatively, stacking reduces the random noise to 1 / √n, where n is the number of stacks:

Figure 4:

Random noise is reduced to 1 / √n. This table shows how the amplitude of the noise decreases with increasing stacks. Stacking 100 times decreases the noise to 10% or 10 times smaller. Stacking 10,000 times decreases the noise to 1% or 100 times smaller – this is 2 orders of magnitude smaller.

Here is an example of this noise reduction achieved by stacking. The data below was collected with the pulseEKKO® Ultra receiver along the same GPR line, varying the number of stacks. You can see how the amplitude of the random noise is reduced as the number of stacks increases.

Figure 5:

Quantitative field results from data collected at the site in Figure 1. The noise floor drops as the number of stacks increases (left). The depth of GPR penetration is the time at which the GPR signals intersect with the noise floor. As the number of stacks increases, the depth of penetration increases from 425ns to 900ns (right).

The result of reducing the amplitude of the random noise by stacking, is an increase in the depth of penetration from 425ns to 900ns; about double.

This advancement in technology will fundamentally change what geoscientists can achieve with ground penetrating radar. Sensors & Software prides itself on being on the cutting edge of GPR advancements. To learn more, contact us.